This invention relates generally to adhesive tape structures, and more particularly to adhesive tape structures which are used in conjunction with insulation for fluid conduits.
Most heating and air conditioning units in dwellings, commercial buildings and industrial plants include cylindrical pipes which carry heated or cooled air or water or steam. In addition, in industrial applications, pipes may be used to carry these and other fluids. In most instances, particularly in more severe climates, these pipes must be insulated to prevent freezing, and/or to maintain the temperature of the fluid within the pipes, especially where the pipes are disposed on the exterior of the building structure.
Insulation segments may be used to insulate such pipes. These segments typically are cylindrical in shape and include an inner insulating layer surrounded by a jacket. In the center of the segments is a cylindrical passageway extending axially or longitudinally along the segment and having a diameter roughly equal to the outside diameter of the pipe to be insulated. A longitudinal slit is provided extending from one end of the segment to the other. This slit may be opened to allow insertion of the pipe therethrough and into the central passageway. A flap is provided for covering the slit and for sealing the pipe within the segment. Such segments typically extend along a pipe in an end to end, abutting relationship to fully insulate and seal the pipe.
The inner insulating layer in each segment typically is formed of a fiberglass or mineral wool, a foamed cellular fiberglass or a rigid foam. The jacket which covers the insulating layer typically is formed of a metal or metalized foil, and/or a layer of kraft paper or the like. A preferred jacket material is an All Service Jacket (ASJ), which has layers that include paper, scrim, and aluminum foil and/or metalized polyester. Often, the metal or metalized layers and/or paper layers are laminated together to provide a weather-tight structure with a suitable tear and tensile strength. Typically the flap which covers the slit is merely an extension of the jacket and is formed of the same materials.
Often, the flap and/or the outer surface of the insulation jacket adjacent the slit is provided with a strip of adhesive or adhesive tape to bond the flap to the outer surface of the jacket to cover and seal the slit. The actual sealing of the flap to the jacket typically occurs at the job site when the insulation is installed. It is desirable, if not necessary, to keep the bonding surfaces of the flap and the confronting, outer surface of the jacket free from dirt and moisture to permit a tight seal. If the seal is not satisfactory, xe2x80x9cfish mouthingxe2x80x9d can occur either as a result of the breakdown of the bond between the adhesive strip and the flap, or the bond between the adhesive strip and the outer surface of the jacket. This breakdown can produce delamination or disintegration of the jacket or the flap which can occur over a period of a few weeks in a very damp environment, or over a period of many months in less damp environments. If such xe2x80x9cfish mouthingxe2x80x9d occurs, the insulation segments must be removed and replaced if the desired level of protection is to be maintained xe2x80x9cFish mouthingxe2x80x9d is a particular problem on jobs for the United States Government, since such xe2x80x9cfish mouthingxe2x80x9d does not meet its specifications and the contractor may be required to return to the job site and repair the damage at his or her own cost.
Moreover, hot melt adhesives typically are used to bond the jacket to the inner insulating layer. The insulation segments typically are still hot, and the adhesive is still soft and not yet cured, when the insulation segments are placed in containers for shipment. This quick placement in containers is necessary to expedite the manufacturing and shipping process. The containers into which the segments are placed tend to act as insulators and retain the heat within the container maintaining the hot melt adhesive in a softened condition for a prolonged period of time after placement in the containers. As a result, the jacket can separate from the inner insulating layer prior to cooling and curing, and prior to arrival of the segment at the job site. Such separated segments are not acceptable, and must either be discarded or reattached. Obviously, this repair or replacement is very costly. To overcome this problem, harder, more quickly curing adhesives have been used to bond the jacket to the inner insulating layer. However, since these harder adhesives do not permit movement of the jacket with respect to the inner insulating layer with time and under charging temperature and moisture conditions, unacceptable dimpling of the jacket often occurs with such adhesives.
One solution to the foregoing problems is to use soft, hot melt adhesives or two component urethane adhesives and to temporarily seal the flap to the outer surface of the insulation jacket at the-factory prior to shipping. This solution protects the surfaces to be adhered to one another to minimize any xe2x80x9cfish mouthingxe2x80x9d effects. This solution also wraps the jacket tightly about the inner insulating layer, and prevents separation of the structure during shipment because of the soft or uncured condition of the hot melt adhesive. This solution also avoids most dimpling effects. One existing structure that provides such a solution is found in U.S. Pat. No. 4,157,410. In this structure, tape is provided having either two or four layers of pressure sensitive adhesive separated by release liners. When applied to the insulation jacket and flap at the factory, the outer two release liners are removed, exposing a layer of pressure sensitive adhesive on either side of the structure which then temporarily bonds the flap to the outer surface of the insulation jacket. When it is desired to install the insulation segment at the job site, the flap is separated from the outer surface of the jacket by prying apart the structure along a central release liner in the structure that separates two adhesive layers. The central release liner is then removed, and the two adhesive layers are bonded together to permanently seal the flap to the outer surface of the insulation jacket.
Another solution is that disclosed in U.S. Pat. No. 5,104,701 assigned to the assignee of the present application. In the closure system of this ""701 patent, a tape contains a layer of a low tack, pressure sensitive adhesive which bonds the tape on one side to a strip either on the outer surface of the jacket on one side of the slit or on the flap. The opposite side of the tape has a release liner to which a high tack adhesive layer on the other of the flap or the outer surface of the jacket is bonded to temporarily bond the flap to the outer surface of the jacket. The tape structure can be opened at the job site by peeling the adhesive layer on the tape away from the strip. Once the flap is opened, the release liner is removed and the high tack adhesive layer on the flap or jacket may be permanently bonded respectively to the outer surface of the jacket or the flap to provide a permanent seal.
Another structure is found in U.S. Pat. No. 5,964,252, in which an abridged release liner is provided to allow partial exposure of the adhesive layer to achieve a temporary bond. This temporary bond may be severed and the release liner may be subsequently removed to achieve a permanent bond.
Another existing prior art structure in which an adhesive layer is disposed on one of the flap and the outer surface of the jacket is disclosed in U.S. Pat. No. 5,104,701. In one embodiment of this prior art structure, an adhesive tape is provided which can be bonded to the underside of the flap or to the outer surface of the jacket, either at the job site or at the factory. This tape typically includes a substrate having a layer of a pressure sensitive adhesive disposed on both sides thereof. The adhesive layer on one side of the substrate is bonded to the inside surface of the flap or to the jacket, while the adhesive layer on the other side of the substrate is covered by a release liner typically having a silicon coated surface. This tape is either cut or provided in strips which are adhered on the exposed adhesive side to the underside of the flap or to the outer surface of the jacket. At the job site, the insulation is wrapped about the pipe, the release liner is removed from the adhesive layer on the other side of the substrate, and the newly exposed adhesive layer then bonds the flap to the outer surface of the jacket of the insulation segment.
While the foregoing closure systems solve some of the problems associated with cylindrical pipe insulation, these closure systems are somewhat complicated, and therefore more expensive than desired.
This invention relates generally to an adhesive tape structure which may be used as a temporary closure and as a permanent closure for a flap for an insulation segment for a fluid conduit. The tape structure of this invention retains the insulation segment in a closed condition after manufacture and during shipment to prevent separation of the jacket and the inner insulating layer. Moreover, the temporary closure maintains the surfaces to be joined on the underside of the flap and the outer surface of the jacket in a clean and dry condition. The temporary seal is easily broken, and the permanent seal may be readily effected at the job site after wrapping the insulation segment about a pipe. The closure system of the present invention is simpler and therefore less complicated to use and less expensive to manufacture than some prior art closure systems.
In one aspect, this invention discloses an elongated tape structure which includes a substrate, a first layer of a pressure sensitive adhesive disposed on one surface of the substrate, a second layer of a pressure sensitive adhesive disposed on another surface of the substrate and a release liner which covers the second layer of pressure sensitive adhesive. The release liner is formed of first and second portions which are separated along a line extending in a direction of elongation of the tape structure. In one embodiment of this aspect, the first portion of the release liner is substantially wider than the second portion as measured in a direction transverse to the direction of elongation of the tape structure. In another embodiment, the second layer of pressure sensitive adhesive includes a gap having no adhesive which is aligned with and extends along the line separating the first and second portions of the release liner. In yet another embodiment, a tab is disposed on the first portion of the release liner for removal of the first portion of the release liner separately from the second portion. In another embodiment, there is a tab disposed on the second portion of the release liner for removal of the second portion of the release liner separately from the first portion.
In yet another embodiment, there is a tab disposed on the second portion of the release liner along an edge of the second portion facing the first portion of the release liner and overlying the gap. The tab is graspable for removal of the second portion of the release liner. In yet another embodiment of this aspect, there is a tab disposed on the first portion of the release liner along an edge of the first portion facing the second portion of the release liner and overlying the gap. This tab is also graspable for removal of the first portion of the release liner from the second layer of pressure sensitive adhesive.
In another aspect, a temporary closure between a flap and an outer surface of a jacket of an insulation segment is disclosed. The jacket includes a slit extending in the direction of elongation, and the flap is used to cover the slit. In this aspect, the temporary closure includes a substrate, a first layer of a pressure sensitive adhesive disposed on one side of the substrate and adhered to a selected one of the underside of the flap and an outer surface of the jacket, a second layer of a pressure sensitive adhesive disposed on another side of the substrate, and a release liner covering a first portion of the second layer of pressure sensitive adhesive to allow a second portion of the second layer of pressure sensitive adhesive to bond to the other of the underside of the flap and the outer surface of the jacket. In one embodiment of this aspect, the second portion of the second layer of pressure sensitive adhesive is positioned on a side of the slit in the insulation jacket facing a distal end of the flap. In another embodiment, the release liner is removable from the first portion of the second layer of pressure sensitive adhesive after breaking of a bond between the second portion of the second layer of pressure sensitive adhesive and the other of the underside of the flap and the outer surface of the insulation jacket, to allow the first portion of the second layer of pressure sensitive adhesive to be bonded to the other of the underside of the flap and the outer surface of the insulation jacket. In another embodiment, the closure is spaced from a distal end of the flap to provide an extension on the flap for grasping by a user to break the bond between the second portion of the second layer of pressure sensitive adhesive and the other of the underside of the flap and the outer surface of the insulation jacket.
In yet another embodiment of this aspect, the first layer of pressure sensitive adhesive is bonded to the underside of the flap, and the closure covers the slit in the insulation jacket. In this embodiment, the second portion of the second layer of pressure sensitive adhesive is adhered to the outer surface of the jacket on a side of the slit facing a distal end of the flap. In another embodiment, the first layer of pressure sensitive adhesive is bonded to the outer surface of the insulation jacket on a side of the slit facing the distal end of the flap, and the second portion of the second layer of pressure sensitive adhesive is bonded to the underside of the flap. In yet another embodiment, the second portion of the second layer of pressure sensitive adhesive is substantially narrower in width than the first portion in a direction transverse to the direction of elongation of the insulation segment.
In another aspect of the invention, a method for insulating a pipe is disclosed which uses an elongated cylindrical insulation segment having an outer jacket, a slit in the outer jacket extending in the direction of elongation of the segment to a central passageway for insertion of a pipe into the central passageway, and a flap for covering the slit in the outer jacket. This method includes providing a tape structure having a substrate, a first layer of a pressure sensitive adhesive disposed on one side of the substrate, a second layer of a pressure sensitive adhesive disposed on the other side of the substrate, and a release liner covering the second layer of pressure sensitive adhesive, bonding the tape structure along the first layer of pressure sensitive adhesive to a selected one of the underside of the flap and an outer surface of the insulation jacket, removing a narrow strip of the release liner to expose a narrow strip of adhesive on the second layer of pressure sensitive adhesive, and bonding the narrow strip of adhesive on the second layer of pressure sensitive adhesive to the other of the underside of the flap and the outer surface of the outer jacket to provide a temporary seal for shipment of the insulation segment to a job site. In one embodiment, the narrow strip of adhesive is bonded to the other of the underside of the flap and the outer surface of the insulation jacket on a side of slit facing a distal end of the flap. The method of this aspect may also further include breaking the temporary seal between the narrow strip of adhesive on the second layer of pressure sensitive adhesive and the other the underside of the flap and the outer surface of the outer jacket, inserting a pipe into the central passageway through the slit, removing the release liner from the second layer of pressure sensitive adhesive, and adhering the second layer of pressure sensitive adhesive to the other of the underside of the flap and the outer surface of the outer jacket.
In another embodiment, the removing step includes grasping the release liner by a tab and pulling the release liner from the second layer of pressure sensitive adhesive. In another embodiment, the step of bonding the tape may comprise adhering the first layer of pressure sensitive adhesive to the underside of the flap, and the step of bonding the narrow strip may comprise bonding the narrow strip of adhesive on the second layer of pressure sensitive adhesive to the outer surface of the outer jacket on a side of the slit facing a distal end of the flap.
In another embodiment of the method of this invention, a step of bonding the tape may comprise adhering the first layer of pressure sensitive adhesive to the outer surface of the outer jacket on a side of the slit facing the distal end of the flap, and the step of bonding the narrow strip of adhesive may comprise adhering the narrow strip of adhesive on the second layer of pressure sensitive adhesive to the underside of the flap. In yet another embodiment, the step of breaking the temporary seal comprises grasping an extension of the flap and pulling the flap away from the outer surface of the outer jacket. In yet another embodiment of the method of this invention, the release liner may be scored to separate the release liner into a narrow strip and a second strip substantially wider than the narrow strip in a direction transverse to the direction of elongation of the insulation segment. This scoring step may be performed after the step of bonding the tape and before the removing step. In yet another embodiment, the method may comprise providing a gap in the second layer of pressure sensitive adhesive. In another embodiment, the release liner is scored along a line aligned with the gap in the second layer of pressure sensitive adhesive to divide the release liner into two strips, the narrow strip and the second strip which is substantially wider than the narrow strip.